]> git.bitcoin.ninja Git - rust-lightning/commitdiff
Create ChannelContext constructor for inbound channels
authorDuncan Dean <git@dunxen.dev>
Fri, 24 Nov 2023 07:32:56 +0000 (09:32 +0200)
committerDuncan Dean <git@dunxen.dev>
Tue, 20 Feb 2024 07:15:13 +0000 (09:15 +0200)
lightning/src/ln/channel.rs

index 2ae44fb0eb0386ac41c4a29715ee8be72c39a009..ed2350839545d7f9029b52fac0a50ace91adec9d 100644 (file)
@@ -1503,6 +1503,338 @@ pub(super) struct ChannelContext<SP: Deref> where SP::Target: SignerProvider {
 }
 
 impl<SP: Deref> ChannelContext<SP> where SP::Target: SignerProvider  {
+       fn new_for_inbound_channel<'a, ES: Deref, F: Deref, L: Deref>(
+               fee_estimator: &'a LowerBoundedFeeEstimator<F>,
+               entropy_source: &'a ES,
+               signer_provider: &'a SP,
+               counterparty_node_id: PublicKey,
+               their_features: &'a InitFeatures,
+               user_id: u128,
+               config: &'a UserConfig,
+               current_chain_height: u32,
+               logger: &'a L,
+               is_0conf: bool,
+               our_funding_satoshis: u64,
+               counterparty_pubkeys: ChannelPublicKeys,
+               channel_type: ChannelTypeFeatures,
+               holder_selected_channel_reserve_satoshis: u64,
+               msg_channel_reserve_satoshis: u64,
+               msg_push_msat: u64,
+               open_channel_fields: msgs::CommonOpenChannelFields,
+       ) -> Result<ChannelContext<SP>, ChannelError>
+               where
+                       ES::Target: EntropySource,
+                       F::Target: FeeEstimator,
+                       L::Target: Logger,
+                       SP::Target: SignerProvider,
+       {
+               let logger = WithContext::from(logger, Some(counterparty_node_id), Some(open_channel_fields.temporary_channel_id));
+               let announced_channel = if (open_channel_fields.channel_flags & 1) == 1 { true } else { false };
+
+               let channel_value_satoshis = our_funding_satoshis.saturating_add(open_channel_fields.funding_satoshis);
+
+               let channel_keys_id = signer_provider.generate_channel_keys_id(true, channel_value_satoshis, user_id);
+               let holder_signer = signer_provider.derive_channel_signer(channel_value_satoshis, channel_keys_id);
+               let pubkeys = holder_signer.pubkeys().clone();
+
+               if config.channel_handshake_config.our_to_self_delay < BREAKDOWN_TIMEOUT {
+                       return Err(ChannelError::Close(format!("Configured with an unreasonable our_to_self_delay ({}) putting user funds at risks. It must be greater than {}", config.channel_handshake_config.our_to_self_delay, BREAKDOWN_TIMEOUT)));
+               }
+
+               // Check sanity of message fields:
+               if channel_value_satoshis > config.channel_handshake_limits.max_funding_satoshis {
+                       return Err(ChannelError::Close(format!(
+                               "Per our config, funding must be at most {}. It was {}. Peer contribution: {}. Our contribution: {}",
+                               config.channel_handshake_limits.max_funding_satoshis, channel_value_satoshis,
+                               open_channel_fields.funding_satoshis, our_funding_satoshis)));
+               }
+               if channel_value_satoshis >= TOTAL_BITCOIN_SUPPLY_SATOSHIS {
+                       return Err(ChannelError::Close(format!("Funding must be smaller than the total bitcoin supply. It was {}", channel_value_satoshis)));
+               }
+               if msg_channel_reserve_satoshis > channel_value_satoshis {
+                       return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must be no greater than channel_value_satoshis: {}", msg_channel_reserve_satoshis, channel_value_satoshis)));
+               }
+               let full_channel_value_msat = (channel_value_satoshis - msg_channel_reserve_satoshis) * 1000;
+               if msg_push_msat > full_channel_value_msat {
+                       return Err(ChannelError::Close(format!("push_msat {} was larger than channel amount minus reserve ({})", msg_push_msat, full_channel_value_msat)));
+               }
+               if open_channel_fields.dust_limit_satoshis > channel_value_satoshis {
+                       return Err(ChannelError::Close(format!("dust_limit_satoshis {} was larger than channel_value_satoshis {}. Peer never wants payout outputs?", open_channel_fields.dust_limit_satoshis, channel_value_satoshis)));
+               }
+               if open_channel_fields.htlc_minimum_msat >= full_channel_value_msat {
+                       return Err(ChannelError::Close(format!("Minimum htlc value ({}) was larger than full channel value ({})", open_channel_fields.htlc_minimum_msat, full_channel_value_msat)));
+               }
+               Channel::<SP>::check_remote_fee(&channel_type, fee_estimator, open_channel_fields.commitment_feerate_sat_per_1000_weight, None, &&logger)?;
+
+               let max_counterparty_selected_contest_delay = u16::min(config.channel_handshake_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
+               if open_channel_fields.to_self_delay > max_counterparty_selected_contest_delay {
+                       return Err(ChannelError::Close(format!("They wanted our payments to be delayed by a needlessly long period. Upper limit: {}. Actual: {}", max_counterparty_selected_contest_delay, open_channel_fields.to_self_delay)));
+               }
+               if open_channel_fields.max_accepted_htlcs < 1 {
+                       return Err(ChannelError::Close("0 max_accepted_htlcs makes for a useless channel".to_owned()));
+               }
+               if open_channel_fields.max_accepted_htlcs > MAX_HTLCS {
+                       return Err(ChannelError::Close(format!("max_accepted_htlcs was {}. It must not be larger than {}", open_channel_fields.max_accepted_htlcs, MAX_HTLCS)));
+               }
+
+               // Now check against optional parameters as set by config...
+               if channel_value_satoshis < config.channel_handshake_limits.min_funding_satoshis {
+                       return Err(ChannelError::Close(format!("Funding satoshis ({}) is less than the user specified limit ({})", channel_value_satoshis, config.channel_handshake_limits.min_funding_satoshis)));
+               }
+               if open_channel_fields.htlc_minimum_msat > config.channel_handshake_limits.max_htlc_minimum_msat {
+                       return Err(ChannelError::Close(format!("htlc_minimum_msat ({}) is higher than the user specified limit ({})", open_channel_fields.htlc_minimum_msat, config.channel_handshake_limits.max_htlc_minimum_msat)));
+               }
+               if open_channel_fields.max_htlc_value_in_flight_msat < config.channel_handshake_limits.min_max_htlc_value_in_flight_msat {
+                       return Err(ChannelError::Close(format!("max_htlc_value_in_flight_msat ({}) is less than the user specified limit ({})", open_channel_fields.max_htlc_value_in_flight_msat, config.channel_handshake_limits.min_max_htlc_value_in_flight_msat)));
+               }
+               if msg_channel_reserve_satoshis > config.channel_handshake_limits.max_channel_reserve_satoshis {
+                       return Err(ChannelError::Close(format!("channel_reserve_satoshis ({}) is higher than the user specified limit ({})", msg_channel_reserve_satoshis, config.channel_handshake_limits.max_channel_reserve_satoshis)));
+               }
+               if open_channel_fields.max_accepted_htlcs < config.channel_handshake_limits.min_max_accepted_htlcs {
+                       return Err(ChannelError::Close(format!("max_accepted_htlcs ({}) is less than the user specified limit ({})", open_channel_fields.max_accepted_htlcs, config.channel_handshake_limits.min_max_accepted_htlcs)));
+               }
+               if open_channel_fields.dust_limit_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
+                       return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is less than the implementation limit ({})", open_channel_fields.dust_limit_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
+               }
+               if open_channel_fields.dust_limit_satoshis >  MAX_CHAN_DUST_LIMIT_SATOSHIS {
+                       return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is greater than the implementation limit ({})", open_channel_fields.dust_limit_satoshis, MAX_CHAN_DUST_LIMIT_SATOSHIS)));
+               }
+
+               // Convert things into internal flags and prep our state:
+
+               if config.channel_handshake_limits.force_announced_channel_preference {
+                       if config.channel_handshake_config.announced_channel != announced_channel {
+                               return Err(ChannelError::Close("Peer tried to open channel but their announcement preference is different from ours".to_owned()));
+                       }
+               }
+
+               if holder_selected_channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
+                       // Protocol level safety check in place, although it should never happen because
+                       // of `MIN_THEIR_CHAN_RESERVE_SATOSHIS`
+                       return Err(ChannelError::Close(format!("Suitable channel reserve not found. remote_channel_reserve was ({}). dust_limit_satoshis is ({}).", holder_selected_channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
+               }
+               if holder_selected_channel_reserve_satoshis * 1000 >= full_channel_value_msat {
+                       return Err(ChannelError::Close(format!("Suitable channel reserve not found. remote_channel_reserve was ({})msats. Channel value is ({} - {})msats.", holder_selected_channel_reserve_satoshis * 1000, full_channel_value_msat, msg_push_msat)));
+               }
+               if msg_channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
+                       log_debug!(logger, "channel_reserve_satoshis ({}) is smaller than our dust limit ({}). We can broadcast stale states without any risk, implying this channel is very insecure for our counterparty.",
+                               msg_channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS);
+               }
+               if holder_selected_channel_reserve_satoshis < open_channel_fields.dust_limit_satoshis {
+                       return Err(ChannelError::Close(format!("Dust limit ({}) too high for the channel reserve we require the remote to keep ({})", open_channel_fields.dust_limit_satoshis, holder_selected_channel_reserve_satoshis)));
+               }
+
+               // check if the funder's amount for the initial commitment tx is sufficient
+               // for full fee payment plus a few HTLCs to ensure the channel will be useful.
+               let anchor_outputs_value = if channel_type.supports_anchors_zero_fee_htlc_tx() {
+                       ANCHOR_OUTPUT_VALUE_SATOSHI * 2
+               } else {
+                       0
+               };
+               let funders_amount_msat = open_channel_fields.funding_satoshis * 1000 - msg_push_msat;
+               let commitment_tx_fee = commit_tx_fee_msat(open_channel_fields.commitment_feerate_sat_per_1000_weight, MIN_AFFORDABLE_HTLC_COUNT, &channel_type) / 1000;
+               if (funders_amount_msat / 1000).saturating_sub(anchor_outputs_value) < commitment_tx_fee {
+                       return Err(ChannelError::Close(format!("Funding amount ({} sats) can't even pay fee for initial commitment transaction fee of {} sats.", (funders_amount_msat / 1000).saturating_sub(anchor_outputs_value), commitment_tx_fee)));
+               }
+
+               let to_remote_satoshis = funders_amount_msat / 1000 - commitment_tx_fee - anchor_outputs_value;
+               // While it's reasonable for us to not meet the channel reserve initially (if they don't
+               // want to push much to us), our counterparty should always have more than our reserve.
+               if to_remote_satoshis < holder_selected_channel_reserve_satoshis {
+                       return Err(ChannelError::Close("Insufficient funding amount for initial reserve".to_owned()));
+               }
+
+               let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
+                       match &open_channel_fields.shutdown_scriptpubkey {
+                               &Some(ref script) => {
+                                       // Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
+                                       if script.len() == 0 {
+                                               None
+                                       } else {
+                                               if !script::is_bolt2_compliant(&script, their_features) {
+                                                       return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided an unacceptable scriptpubkey format: {}", script)))
+                                               }
+                                               Some(script.clone())
+                                       }
+                               },
+                               // Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
+                               &None => {
+                                       return Err(ChannelError::Close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out".to_owned()));
+                               }
+                       }
+               } else { None };
+
+               let shutdown_scriptpubkey = if config.channel_handshake_config.commit_upfront_shutdown_pubkey {
+                       match signer_provider.get_shutdown_scriptpubkey() {
+                               Ok(scriptpubkey) => Some(scriptpubkey),
+                               Err(_) => return Err(ChannelError::Close("Failed to get upfront shutdown scriptpubkey".to_owned())),
+                       }
+               } else { None };
+
+               if let Some(shutdown_scriptpubkey) = &shutdown_scriptpubkey {
+                       if !shutdown_scriptpubkey.is_compatible(&their_features) {
+                               return Err(ChannelError::Close(format!("Provided a scriptpubkey format not accepted by peer: {}", shutdown_scriptpubkey)));
+                       }
+               }
+
+               let destination_script = match signer_provider.get_destination_script(channel_keys_id) {
+                       Ok(script) => script,
+                       Err(_) => return Err(ChannelError::Close("Failed to get destination script".to_owned())),
+               };
+
+               let mut secp_ctx = Secp256k1::new();
+               secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
+
+               let minimum_depth = if is_0conf {
+                       Some(0)
+               } else {
+                       Some(cmp::max(config.channel_handshake_config.minimum_depth, 1))
+               };
+
+               let value_to_self_msat = our_funding_satoshis * 1000 + msg_push_msat;
+
+               // TODO(dual_funding): Checks for `funding_feerate_sat_per_1000_weight`?
+
+               let channel_context = ChannelContext {
+                       user_id,
+
+                       config: LegacyChannelConfig {
+                               options: config.channel_config.clone(),
+                               announced_channel,
+                               commit_upfront_shutdown_pubkey: config.channel_handshake_config.commit_upfront_shutdown_pubkey,
+                       },
+
+                       prev_config: None,
+
+                       inbound_handshake_limits_override: None,
+
+                       temporary_channel_id: Some(open_channel_fields.temporary_channel_id),
+                       channel_id: open_channel_fields.temporary_channel_id,
+                       channel_state: ChannelState::NegotiatingFunding(
+                               NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT
+                       ),
+                       announcement_sigs_state: AnnouncementSigsState::NotSent,
+                       secp_ctx,
+
+                       latest_monitor_update_id: 0,
+
+                       holder_signer: ChannelSignerType::Ecdsa(holder_signer),
+                       shutdown_scriptpubkey,
+                       destination_script,
+
+                       cur_holder_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
+                       cur_counterparty_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
+                       value_to_self_msat,
+
+                       pending_inbound_htlcs: Vec::new(),
+                       pending_outbound_htlcs: Vec::new(),
+                       holding_cell_htlc_updates: Vec::new(),
+                       pending_update_fee: None,
+                       holding_cell_update_fee: None,
+                       next_holder_htlc_id: 0,
+                       next_counterparty_htlc_id: 0,
+                       update_time_counter: 1,
+
+                       resend_order: RAACommitmentOrder::CommitmentFirst,
+
+                       monitor_pending_channel_ready: false,
+                       monitor_pending_revoke_and_ack: false,
+                       monitor_pending_commitment_signed: false,
+                       monitor_pending_forwards: Vec::new(),
+                       monitor_pending_failures: Vec::new(),
+                       monitor_pending_finalized_fulfills: Vec::new(),
+
+                       signer_pending_commitment_update: false,
+                       signer_pending_funding: false,
+
+
+                       #[cfg(debug_assertions)]
+                       holder_max_commitment_tx_output: Mutex::new((value_to_self_msat, (channel_value_satoshis * 1000 - msg_push_msat).saturating_sub(value_to_self_msat))),
+                       #[cfg(debug_assertions)]
+                       counterparty_max_commitment_tx_output: Mutex::new((value_to_self_msat, (channel_value_satoshis * 1000 - msg_push_msat).saturating_sub(value_to_self_msat))),
+
+                       last_sent_closing_fee: None,
+                       pending_counterparty_closing_signed: None,
+                       expecting_peer_commitment_signed: false,
+                       closing_fee_limits: None,
+                       target_closing_feerate_sats_per_kw: None,
+
+                       funding_tx_confirmed_in: None,
+                       funding_tx_confirmation_height: 0,
+                       short_channel_id: None,
+                       channel_creation_height: current_chain_height,
+
+                       feerate_per_kw: open_channel_fields.commitment_feerate_sat_per_1000_weight,
+                       channel_value_satoshis,
+                       counterparty_dust_limit_satoshis: open_channel_fields.dust_limit_satoshis,
+                       holder_dust_limit_satoshis: MIN_CHAN_DUST_LIMIT_SATOSHIS,
+                       counterparty_max_htlc_value_in_flight_msat: cmp::min(open_channel_fields.max_htlc_value_in_flight_msat, channel_value_satoshis * 1000),
+                       holder_max_htlc_value_in_flight_msat: get_holder_max_htlc_value_in_flight_msat(channel_value_satoshis, &config.channel_handshake_config),
+                       counterparty_selected_channel_reserve_satoshis: Some(msg_channel_reserve_satoshis),
+                       holder_selected_channel_reserve_satoshis,
+                       counterparty_htlc_minimum_msat: open_channel_fields.htlc_minimum_msat,
+                       holder_htlc_minimum_msat: if config.channel_handshake_config.our_htlc_minimum_msat == 0 { 1 } else { config.channel_handshake_config.our_htlc_minimum_msat },
+                       counterparty_max_accepted_htlcs: open_channel_fields.max_accepted_htlcs,
+                       holder_max_accepted_htlcs: cmp::min(config.channel_handshake_config.our_max_accepted_htlcs, MAX_HTLCS),
+                       minimum_depth,
+
+                       counterparty_forwarding_info: None,
+
+                       channel_transaction_parameters: ChannelTransactionParameters {
+                               holder_pubkeys: pubkeys,
+                               holder_selected_contest_delay: config.channel_handshake_config.our_to_self_delay,
+                               is_outbound_from_holder: false,
+                               counterparty_parameters: Some(CounterpartyChannelTransactionParameters {
+                                       selected_contest_delay: open_channel_fields.to_self_delay,
+                                       pubkeys: counterparty_pubkeys,
+                               }),
+                               funding_outpoint: None,
+                               channel_type_features: channel_type.clone()
+                       },
+                       funding_transaction: None,
+                       is_batch_funding: None,
+
+                       counterparty_cur_commitment_point: Some(open_channel_fields.first_per_commitment_point),
+                       counterparty_prev_commitment_point: None,
+                       counterparty_node_id,
+
+                       counterparty_shutdown_scriptpubkey,
+
+                       commitment_secrets: CounterpartyCommitmentSecrets::new(),
+
+                       channel_update_status: ChannelUpdateStatus::Enabled,
+                       closing_signed_in_flight: false,
+
+                       announcement_sigs: None,
+
+                       #[cfg(any(test, fuzzing))]
+                       next_local_commitment_tx_fee_info_cached: Mutex::new(None),
+                       #[cfg(any(test, fuzzing))]
+                       next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
+
+                       workaround_lnd_bug_4006: None,
+                       sent_message_awaiting_response: None,
+
+                       latest_inbound_scid_alias: None,
+                       outbound_scid_alias: 0,
+
+                       channel_pending_event_emitted: false,
+                       channel_ready_event_emitted: false,
+
+                       #[cfg(any(test, fuzzing))]
+                       historical_inbound_htlc_fulfills: new_hash_set(),
+
+                       channel_type,
+                       channel_keys_id,
+
+                       local_initiated_shutdown: None,
+
+                       blocked_monitor_updates: Vec::new(),
+               };
+
+               Ok(channel_context)
+       }
+
        /// Allowed in any state (including after shutdown)
        pub fn get_update_time_counter(&self) -> u32 {
                self.update_time_counter
@@ -7295,15 +7627,12 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                          L::Target: Logger,
        {
                let logger = WithContext::from(logger, Some(counterparty_node_id), Some(msg.common_fields.temporary_channel_id));
-               let announced_channel = if (msg.common_fields.channel_flags & 1) == 1 { true } else { false };
 
                // First check the channel type is known, failing before we do anything else if we don't
                // support this channel type.
                let channel_type = channel_type_from_open_channel(msg, their_features, our_supported_features)?;
 
-               let channel_keys_id = signer_provider.generate_channel_keys_id(true, msg.common_fields.funding_satoshis, user_id);
-               let holder_signer = signer_provider.derive_channel_signer(msg.common_fields.funding_satoshis, channel_keys_id);
-               let pubkeys = holder_signer.pubkeys().clone();
+               let holder_selected_channel_reserve_satoshis = get_holder_selected_channel_reserve_satoshis(msg.common_fields.funding_satoshis, config);
                let counterparty_pubkeys = ChannelPublicKeys {
                        funding_pubkey: msg.common_fields.funding_pubkey,
                        revocation_basepoint: RevocationBasepoint::from(msg.common_fields.revocation_basepoint),
@@ -7312,297 +7641,29 @@ impl<SP: Deref> InboundV1Channel<SP> where SP::Target: SignerProvider {
                        htlc_basepoint: HtlcBasepoint::from(msg.common_fields.htlc_basepoint)
                };
 
-               if config.channel_handshake_config.our_to_self_delay < BREAKDOWN_TIMEOUT {
-                       return Err(ChannelError::Close(format!("Configured with an unreasonable our_to_self_delay ({}) putting user funds at risks. It must be greater than {}", config.channel_handshake_config.our_to_self_delay, BREAKDOWN_TIMEOUT)));
-               }
-
-               // Check sanity of message fields:
-               if msg.common_fields.funding_satoshis > config.channel_handshake_limits.max_funding_satoshis {
-                       return Err(ChannelError::Close(format!("Per our config, funding must be at most {}. It was {}", config.channel_handshake_limits.max_funding_satoshis, msg.common_fields.funding_satoshis)));
-               }
-               if msg.common_fields.funding_satoshis >= TOTAL_BITCOIN_SUPPLY_SATOSHIS {
-                       return Err(ChannelError::Close(format!("Funding must be smaller than the total bitcoin supply. It was {}", msg.common_fields.funding_satoshis)));
-               }
-               if msg.channel_reserve_satoshis > msg.common_fields.funding_satoshis {
-                       return Err(ChannelError::Close(format!("Bogus channel_reserve_satoshis ({}). Must be not greater than funding_satoshis: {}", msg.channel_reserve_satoshis, msg.common_fields.funding_satoshis)));
-               }
-               let full_channel_value_msat = (msg.common_fields.funding_satoshis - msg.channel_reserve_satoshis) * 1000;
-               if msg.push_msat > full_channel_value_msat {
-                       return Err(ChannelError::Close(format!("push_msat {} was larger than channel amount minus reserve ({})", msg.push_msat, full_channel_value_msat)));
-               }
-               if msg.common_fields.dust_limit_satoshis > msg.common_fields.funding_satoshis {
-                       return Err(ChannelError::Close(format!("dust_limit_satoshis {} was larger than funding_satoshis {}. Peer never wants payout outputs?", msg.common_fields.dust_limit_satoshis, msg.common_fields.funding_satoshis)));
-               }
-               if msg.common_fields.htlc_minimum_msat >= full_channel_value_msat {
-                       return Err(ChannelError::Close(format!("Minimum htlc value ({}) was larger than full channel value ({})", msg.common_fields.htlc_minimum_msat, full_channel_value_msat)));
-               }
-               Channel::<SP>::check_remote_fee(&channel_type, fee_estimator, msg.common_fields.commitment_feerate_sat_per_1000_weight, None, &&logger)?;
-
-               let max_counterparty_selected_contest_delay = u16::min(config.channel_handshake_limits.their_to_self_delay, MAX_LOCAL_BREAKDOWN_TIMEOUT);
-               if msg.common_fields.to_self_delay > max_counterparty_selected_contest_delay {
-                       return Err(ChannelError::Close(format!("They wanted our payments to be delayed by a needlessly long period. Upper limit: {}. Actual: {}", max_counterparty_selected_contest_delay, msg.common_fields.to_self_delay)));
-               }
-               if msg.common_fields.max_accepted_htlcs < 1 {
-                       return Err(ChannelError::Close("0 max_accepted_htlcs makes for a useless channel".to_owned()));
-               }
-               if msg.common_fields.max_accepted_htlcs > MAX_HTLCS {
-                       return Err(ChannelError::Close(format!("max_accepted_htlcs was {}. It must not be larger than {}", msg.common_fields.max_accepted_htlcs, MAX_HTLCS)));
-               }
-
-               // Now check against optional parameters as set by config...
-               if msg.common_fields.funding_satoshis < config.channel_handshake_limits.min_funding_satoshis {
-                       return Err(ChannelError::Close(format!("Funding satoshis ({}) is less than the user specified limit ({})", msg.common_fields.funding_satoshis, config.channel_handshake_limits.min_funding_satoshis)));
-               }
-               if msg.common_fields.htlc_minimum_msat > config.channel_handshake_limits.max_htlc_minimum_msat {
-                       return Err(ChannelError::Close(format!("htlc_minimum_msat ({}) is higher than the user specified limit ({})", msg.common_fields.htlc_minimum_msat,  config.channel_handshake_limits.max_htlc_minimum_msat)));
-               }
-               if msg.common_fields.max_htlc_value_in_flight_msat < config.channel_handshake_limits.min_max_htlc_value_in_flight_msat {
-                       return Err(ChannelError::Close(format!("max_htlc_value_in_flight_msat ({}) is less than the user specified limit ({})", msg.common_fields.max_htlc_value_in_flight_msat, config.channel_handshake_limits.min_max_htlc_value_in_flight_msat)));
-               }
-               if msg.channel_reserve_satoshis > config.channel_handshake_limits.max_channel_reserve_satoshis {
-                       return Err(ChannelError::Close(format!("channel_reserve_satoshis ({}) is higher than the user specified limit ({})", msg.channel_reserve_satoshis, config.channel_handshake_limits.max_channel_reserve_satoshis)));
-               }
-               if msg.common_fields.max_accepted_htlcs < config.channel_handshake_limits.min_max_accepted_htlcs {
-                       return Err(ChannelError::Close(format!("max_accepted_htlcs ({}) is less than the user specified limit ({})", msg.common_fields.max_accepted_htlcs, config.channel_handshake_limits.min_max_accepted_htlcs)));
-               }
-               if msg.common_fields.dust_limit_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
-                       return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is less than the implementation limit ({})", msg.common_fields.dust_limit_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
-               }
-               if msg.common_fields.dust_limit_satoshis >  MAX_CHAN_DUST_LIMIT_SATOSHIS {
-                       return Err(ChannelError::Close(format!("dust_limit_satoshis ({}) is greater than the implementation limit ({})", msg.common_fields.dust_limit_satoshis, MAX_CHAN_DUST_LIMIT_SATOSHIS)));
-               }
-
-               // Convert things into internal flags and prep our state:
-
-               if config.channel_handshake_limits.force_announced_channel_preference {
-                       if config.channel_handshake_config.announced_channel != announced_channel {
-                               return Err(ChannelError::Close("Peer tried to open channel but their announcement preference is different from ours".to_owned()));
-                       }
-               }
-
-               let holder_selected_channel_reserve_satoshis = get_holder_selected_channel_reserve_satoshis(msg.common_fields.funding_satoshis, config);
-               if holder_selected_channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
-                       // Protocol level safety check in place, although it should never happen because
-                       // of `MIN_THEIR_CHAN_RESERVE_SATOSHIS`
-                       return Err(ChannelError::Close(format!("Suitable channel reserve not found. remote_channel_reserve was ({}). dust_limit_satoshis is ({}).", holder_selected_channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS)));
-               }
-               if holder_selected_channel_reserve_satoshis * 1000 >= full_channel_value_msat {
-                       return Err(ChannelError::Close(format!("Suitable channel reserve not found. remote_channel_reserve was ({})msats. Channel value is ({} - {})msats.", holder_selected_channel_reserve_satoshis * 1000, full_channel_value_msat, msg.push_msat)));
-               }
-               if msg.channel_reserve_satoshis < MIN_CHAN_DUST_LIMIT_SATOSHIS {
-                       log_debug!(logger, "channel_reserve_satoshis ({}) is smaller than our dust limit ({}). We can broadcast stale states without any risk, implying this channel is very insecure for our counterparty.",
-                               msg.channel_reserve_satoshis, MIN_CHAN_DUST_LIMIT_SATOSHIS);
-               }
-               if holder_selected_channel_reserve_satoshis < msg.common_fields.dust_limit_satoshis {
-                       return Err(ChannelError::Close(format!("Dust limit ({}) too high for the channel reserve we require the remote to keep ({})", msg.common_fields.dust_limit_satoshis, holder_selected_channel_reserve_satoshis)));
-               }
-
-               // check if the funder's amount for the initial commitment tx is sufficient
-               // for full fee payment plus a few HTLCs to ensure the channel will be useful.
-               let anchor_outputs_value = if channel_type.supports_anchors_zero_fee_htlc_tx() {
-                       ANCHOR_OUTPUT_VALUE_SATOSHI * 2
-               } else {
-                       0
-               };
-               let funders_amount_msat = msg.common_fields.funding_satoshis * 1000 - msg.push_msat;
-               let commitment_tx_fee = commit_tx_fee_msat(msg.common_fields.commitment_feerate_sat_per_1000_weight, MIN_AFFORDABLE_HTLC_COUNT, &channel_type) / 1000;
-               if (funders_amount_msat / 1000).saturating_sub(anchor_outputs_value) < commitment_tx_fee {
-                       return Err(ChannelError::Close(format!("Funding amount ({} sats) can't even pay fee for initial commitment transaction fee of {} sats.", (funders_amount_msat / 1000).saturating_sub(anchor_outputs_value), commitment_tx_fee)));
-               }
-
-               let to_remote_satoshis = funders_amount_msat / 1000 - commitment_tx_fee - anchor_outputs_value;
-               // While it's reasonable for us to not meet the channel reserve initially (if they don't
-               // want to push much to us), our counterparty should always have more than our reserve.
-               if to_remote_satoshis < holder_selected_channel_reserve_satoshis {
-                       return Err(ChannelError::Close("Insufficient funding amount for initial reserve".to_owned()));
-               }
-
-               let counterparty_shutdown_scriptpubkey = if their_features.supports_upfront_shutdown_script() {
-                       match &msg.common_fields.shutdown_scriptpubkey {
-                               &Some(ref script) => {
-                                       // Peer is signaling upfront_shutdown and has opt-out with a 0-length script. We don't enforce anything
-                                       if script.len() == 0 {
-                                               None
-                                       } else {
-                                               if !script::is_bolt2_compliant(&script, their_features) {
-                                                       return Err(ChannelError::Close(format!("Peer is signaling upfront_shutdown but has provided an unacceptable scriptpubkey format: {}", script)))
-                                               }
-                                               Some(script.clone())
-                                       }
-                               },
-                               // Peer is signaling upfront shutdown but don't opt-out with correct mechanism (a.k.a 0-length script). Peer looks buggy, we fail the channel
-                               &None => {
-                                       return Err(ChannelError::Close("Peer is signaling upfront_shutdown but we don't get any script. Use 0-length script to opt-out".to_owned()));
-                               }
-                       }
-               } else { None };
-
-               let shutdown_scriptpubkey = if config.channel_handshake_config.commit_upfront_shutdown_pubkey {
-                       match signer_provider.get_shutdown_scriptpubkey() {
-                               Ok(scriptpubkey) => Some(scriptpubkey),
-                               Err(_) => return Err(ChannelError::Close("Failed to get upfront shutdown scriptpubkey".to_owned())),
-                       }
-               } else { None };
-
-               if let Some(shutdown_scriptpubkey) = &shutdown_scriptpubkey {
-                       if !shutdown_scriptpubkey.is_compatible(&their_features) {
-                               return Err(ChannelError::Close(format!("Provided a scriptpubkey format not accepted by peer: {}", shutdown_scriptpubkey)));
-                       }
-               }
-
-               let destination_script = match signer_provider.get_destination_script(channel_keys_id) {
-                       Ok(script) => script,
-                       Err(_) => return Err(ChannelError::Close("Failed to get destination script".to_owned())),
-               };
-
-               let mut secp_ctx = Secp256k1::new();
-               secp_ctx.seeded_randomize(&entropy_source.get_secure_random_bytes());
-
-               let minimum_depth = if is_0conf {
-                       Some(0)
-               } else {
-                       Some(cmp::max(config.channel_handshake_config.minimum_depth, 1))
-               };
-
                let chan = Self {
-                       context: ChannelContext {
-                               user_id,
-
-                               config: LegacyChannelConfig {
-                                       options: config.channel_config.clone(),
-                                       announced_channel,
-                                       commit_upfront_shutdown_pubkey: config.channel_handshake_config.commit_upfront_shutdown_pubkey,
-                               },
-
-                               prev_config: None,
-
-                               inbound_handshake_limits_override: None,
-
-                               temporary_channel_id: Some(msg.common_fields.temporary_channel_id),
-                               channel_id: msg.common_fields.temporary_channel_id,
-                               channel_state: ChannelState::NegotiatingFunding(
-                                       NegotiatingFundingFlags::OUR_INIT_SENT | NegotiatingFundingFlags::THEIR_INIT_SENT
-                               ),
-                               announcement_sigs_state: AnnouncementSigsState::NotSent,
-                               secp_ctx,
-
-                               latest_monitor_update_id: 0,
-
-                               holder_signer: ChannelSignerType::Ecdsa(holder_signer),
-                               shutdown_scriptpubkey,
-                               destination_script,
-
-                               cur_holder_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
-                               cur_counterparty_commitment_transaction_number: INITIAL_COMMITMENT_NUMBER,
-                               value_to_self_msat: msg.push_msat,
-
-                               pending_inbound_htlcs: Vec::new(),
-                               pending_outbound_htlcs: Vec::new(),
-                               holding_cell_htlc_updates: Vec::new(),
-                               pending_update_fee: None,
-                               holding_cell_update_fee: None,
-                               next_holder_htlc_id: 0,
-                               next_counterparty_htlc_id: 0,
-                               update_time_counter: 1,
-
-                               resend_order: RAACommitmentOrder::CommitmentFirst,
-
-                               monitor_pending_channel_ready: false,
-                               monitor_pending_revoke_and_ack: false,
-                               monitor_pending_commitment_signed: false,
-                               monitor_pending_forwards: Vec::new(),
-                               monitor_pending_failures: Vec::new(),
-                               monitor_pending_finalized_fulfills: Vec::new(),
-
-                               signer_pending_commitment_update: false,
-                               signer_pending_funding: false,
-
-                               #[cfg(debug_assertions)]
-                               holder_max_commitment_tx_output: Mutex::new((msg.push_msat, msg.common_fields.funding_satoshis * 1000 - msg.push_msat)),
-                               #[cfg(debug_assertions)]
-                               counterparty_max_commitment_tx_output: Mutex::new((msg.push_msat, msg.common_fields.funding_satoshis * 1000 - msg.push_msat)),
-
-                               last_sent_closing_fee: None,
-                               pending_counterparty_closing_signed: None,
-                               expecting_peer_commitment_signed: false,
-                               closing_fee_limits: None,
-                               target_closing_feerate_sats_per_kw: None,
-
-                               funding_tx_confirmed_in: None,
-                               funding_tx_confirmation_height: 0,
-                               short_channel_id: None,
-                               channel_creation_height: current_chain_height,
-
-                               feerate_per_kw: msg.common_fields.commitment_feerate_sat_per_1000_weight,
-                               channel_value_satoshis: msg.common_fields.funding_satoshis,
-                               counterparty_dust_limit_satoshis: msg.common_fields.dust_limit_satoshis,
-                               holder_dust_limit_satoshis: MIN_CHAN_DUST_LIMIT_SATOSHIS,
-                               counterparty_max_htlc_value_in_flight_msat: cmp::min(msg.common_fields.max_htlc_value_in_flight_msat, msg.common_fields.funding_satoshis * 1000),
-                               holder_max_htlc_value_in_flight_msat: get_holder_max_htlc_value_in_flight_msat(msg.common_fields.funding_satoshis, &config.channel_handshake_config),
-                               counterparty_selected_channel_reserve_satoshis: Some(msg.channel_reserve_satoshis),
-                               holder_selected_channel_reserve_satoshis,
-                               counterparty_htlc_minimum_msat: msg.common_fields.htlc_minimum_msat,
-                               holder_htlc_minimum_msat: if config.channel_handshake_config.our_htlc_minimum_msat == 0 { 1 } else { config.channel_handshake_config.our_htlc_minimum_msat },
-                               counterparty_max_accepted_htlcs: msg.common_fields.max_accepted_htlcs,
-                               holder_max_accepted_htlcs: cmp::min(config.channel_handshake_config.our_max_accepted_htlcs, MAX_HTLCS),
-                               minimum_depth,
-
-                               counterparty_forwarding_info: None,
-
-                               channel_transaction_parameters: ChannelTransactionParameters {
-                                       holder_pubkeys: pubkeys,
-                                       holder_selected_contest_delay: config.channel_handshake_config.our_to_self_delay,
-                                       is_outbound_from_holder: false,
-                                       counterparty_parameters: Some(CounterpartyChannelTransactionParameters {
-                                               selected_contest_delay: msg.common_fields.to_self_delay,
-                                               pubkeys: counterparty_pubkeys,
-                                       }),
-                                       funding_outpoint: None,
-                                       channel_type_features: channel_type.clone()
-                               },
-                               funding_transaction: None,
-                               is_batch_funding: None,
-
-                               counterparty_cur_commitment_point: Some(msg.common_fields.first_per_commitment_point),
-                               counterparty_prev_commitment_point: None,
+                       context: ChannelContext::new_for_inbound_channel(
+                               fee_estimator,
+                               entropy_source,
+                               signer_provider,
                                counterparty_node_id,
+                               their_features,
+                               user_id,
+                               config,
+                               current_chain_height,
+                               &&logger,
+                               is_0conf,
+                               0,
 
-                               counterparty_shutdown_scriptpubkey,
-
-                               commitment_secrets: CounterpartyCommitmentSecrets::new(),
-
-                               channel_update_status: ChannelUpdateStatus::Enabled,
-                               closing_signed_in_flight: false,
-
-                               announcement_sigs: None,
-
-                               #[cfg(any(test, fuzzing))]
-                               next_local_commitment_tx_fee_info_cached: Mutex::new(None),
-                               #[cfg(any(test, fuzzing))]
-                               next_remote_commitment_tx_fee_info_cached: Mutex::new(None),
-
-                               workaround_lnd_bug_4006: None,
-                               sent_message_awaiting_response: None,
-
-                               latest_inbound_scid_alias: None,
-                               outbound_scid_alias: 0,
-
-                               channel_pending_event_emitted: false,
-                               channel_ready_event_emitted: false,
-
-                               #[cfg(any(test, fuzzing))]
-                               historical_inbound_htlc_fulfills: new_hash_set(),
-
+                               counterparty_pubkeys,
                                channel_type,
-                               channel_keys_id,
-
-                               local_initiated_shutdown: None,
-
-                               blocked_monitor_updates: Vec::new(),
-                       },
+                               holder_selected_channel_reserve_satoshis,
+                               msg.channel_reserve_satoshis,
+                               msg.push_msat,
+                               msg.common_fields.clone(),
+                       )?,
                        unfunded_context: UnfundedChannelContext { unfunded_channel_age_ticks: 0 }
                };
-
                Ok(chan)
        }